There is great interest in the use of aromatic organic molecules, such as acenes, to form semiconductive films in electronic devices as an alternative to conventional inorganic semiconductors, such as silicon. As well known to those of ordinary skill in the art, acenes are polycyclic aromatic hydrocarbons consisting of fused benzene rings in a rectilinear arrangement. For instance, the use of aromatic organic molecules like pentacene instead of silicon would eliminate the costs of silicon processing in the fabrication of thin film field effect transistor (FET) devices. The use of semiconductive films made of aromatic organic molecules could provide other advantages, such as a reduced number of steps for device fabrication, or the ability to produce flexible electronic devices.
Unfortunately, certain conventional synthetic routes for some aromatic organic molecules are undesirable. For example, the conventional synthesis of pentacene as described by Bruckner et al., Tetrahedron Letters (1960) 1:5-6, involves the use of carbon tetrachloride and mercuric chloride. Carbon tetrachloride and mercuric chloride are identified as being toxic. See e.g., Fifth Annual Report on Carcinogens, Substances “Known to be Carcinogenic,” National Toxicology Program, Report NTP 89-239, 1989.
Additionally, pentacene and other acenes have low solubility in organic solvents. This, in turn, deters the use of low-cost solution deposition processes to deposit thin semiconductive films of such molecule in the formation of electronic devices.